论文标题
复合光谱二进制文件，纸XXIII：HD 69479/80，90天二进制
Composite-Spectrum Binaries, Paper XXIII: HD 69479/80, a 90-day binary with a cool-giant primary
论文作者
论文摘要
HD〜69479/80是一种复合谱二进制，其组成部分是G的巨人和早期A矮人。轨道只有91天 （对于包含$ \ sim $ \ sim $ 13太阳半径的系统的系统来说，这似乎很短），而且很小但可能明显非零，偏心率。我们使用频谱减法的过程将组件光谱分开，使用标准的单个巨型光谱作为模板，并发现最接近凉爽分量的光谱为15〜cyg（g8 \，iii）。我们测量了从每个未发现的光谱中测量次级成分的径向速度，求解了系统的SB2轨道，并得出了质量比$ m_1 $ \，/\，/\，$ m_2 $ 1.318。将合成光谱拟合到辅助组件的光谱中，表示9250 \，k，{\ it log} \，g = 3.75的\ teff〜，$ \ sim $ 90 \，\ kmms的旋转速度和旋转速度。我们确定了组件恒星之间的绝对幅度$δ$ V的差异为1.07 mag，晚型组件更明亮。因此，我们可以计算两个组件的半径和亮度，绘制其H-R图位置并拟合进化轨道。最合适的轨道表示巨人的质量为2.9 \，\ msun〜，对于矮人来说，这完全与SB2轨道给出的质量比完全保持一致。矮星的轨道证实，该组件已经开始从ZAM中发展出来。将相应的同句与那些H-R图位置拟合，表明该系统的log \（年龄）约为8.60 Gyr，因为酷星是从ZAM演变而来的，该ZAM比为许多酷巨人分别分别分别的年龄小一点。我们还检测到了巨大成分谱系中的$λ$ \，6707-Å〜LITHIUM线，从而增加了证据表明它接近其红色巨人分支的主要上升的开始。
HD~69479/80 is a composite-spectrum binary whose components are a late-G giant and an early-A dwarf. The orbit has a period of only 91 days (which seems short for a system containing a cool giant with a radius of $\sim$13 solar radii), and a very small, but probably significantly non-zero, eccentricity. We separated the component spectra by a procedure of spectral subtraction, using a standard single giant spectrum as a template, and found the closest match to the spectrum of the cool component to be that of 15~Cyg (G8\,III). We measured the radial velocity of the secondary component from each uncovered spectrum, solved the SB2 orbit for the system, and derived a mass ratio $m_1$\,/\,$m_2$ of 1.318. Fitting synthetic spectra to the spectra of the secondary component indicated a \teff~of 9250\,K, {\it log}\,g = 3.75, and a rotational velocity of $\sim$90\,\kms. We determined the difference in absolute magnitude, $δ$V, between the component stars to be 1.07 mag, the late-type component being the brighter; we could thence calculate radii and luminosities for both components, plot their H--R diagram positions, and fit evolutionary tracks. The best-fitting tracks indicated masses of 2.9\,\msun~for the giant and 2.2\,\msun~for the dwarf, which was fully in keeping with the mass ratio given by the SB2 orbit. The track for the dwarf star confirms that this component has begun to evolve away from the ZAMS. Fitting the corresponding isochrone to those H--R diagram positions indicated a log\,(age) of the system of approximately 8.60 Gyr since the cool star evolved from the ZAMS, which is a little younger than the ages deduced for many cool giants. We also detected the $λ$\,6707-Å~lithium line in the spectrum of the giant component, thus adding to the evidence that it is near the start of its primary ascent of the red-giant branch.
